The objective of this research is to determine the effects of dietary zinc deficiency on lymphocyte function during the different stages of development. The inbred mouse will continue to serve as a model system for study. A fairly complete profile of the effect of zinc deficiency on immunity in the young adult mouse has been developed by our laboratory. In the current application, we propose to study the effects of zinc deficiency on lymphopoiesis. To accomplish this, bone marrow stem cells prepared from zinc-deficient mice will be examined for their ability to migrate to, colonize, and proliferate in the lymphatic organs. In addition, the effect of periods of suboptimal zinc on development of immunity during the fetal-neonatal period will be investigated. Zinc deficiency during ontogeny does alter lymphocyte development as preliminary evidence will demonstrate. In addition, pilot studies suggest that immune damage incurred during development may not be fully repairable upon nutritional repletion. Thus, determining the immune repair capacity of previously zinc-deficient fetal-neonatal mice will represent an additional area of investigation. The studies proposed here, along with past data cited in the progress report should constitute one of the most comprehensive studies of the effects of a nutritional deficiency on lymphocyte function in the mature and developing animal.